The invention relates to a setting plate arrangement for a glass molding machine.
The manufacturing process for hollow glass articles in a glass molding machine starting from their forming in a forming tool to their transfer into an annealing oven is characterized among other things by a perforated setting plate, on which the glass articles arrive in an upright standing position and are subjected to the cooling effect of at least one air flow. This cooling is required to improve the stability of the glass articles, in particular having regard for the immediately following transport processes in the rest of the process operation that are associated with unavoidable mechanical stresses. Previously disclosed is the design of the setting plate as the upper horizontal boundary of a chamber, into which cooling air is introduced, which air exits via orifices in the setting plate and is intended to exert a cooling effect on the glass articles that are standing thereon. A setting plate arrangement of this kind is disclosed by DE 100 39 343 A1 and DE 27 15 647 A1, for example.
Before being transferred to a conveyor belt system discharging into the annealing oven, minimum cooling of the hollow glass articles is thus necessary, although the time unavoidably required for this constitutes a factor that restricts the throughput through the glass molding machine and is accompanied by the requirement for an increase in the cooling intensity. Relatively tight limits are imposed on any increase in the cooling air flow taking into account the stability of the glass vessels and the risk of possible damage. In addition, any changes in the position of the glass articles must also be avoided having regard for the range of action of a sliding transfer mechanism for moving these onto the conveyor belt system once cooling is complete.
Previously disclosed in GB 2 123 402 A is a setting plate arrangement, of which the setting plate is provided with orifices in a uniform pattern and forms the upper boundary of a chamber that is arranged via a central pipe for the generation of a rising flow of cooling air emerging from the orifices, and via an annular gap for the generation of a suction effect and by this means a flow of cooling air that enters via the orifices and is thus downward-oriented. The glass article to be cooled is held initially with the tong-like holders of a take-out mechanism above the setting plate, in conjunction with which a downward-oriented flow of cooling air surrounding the glass article is generated. After a cylindrical enclosing body surrounding the glass article at a distance has been extended from the surface of the setting plate, an upward-oriented flow of cooling air is generated with the intention of producing a cooling effect in particular in the area of the base of the glass article. After the elapse of a predetermined interval of time, the glass article is set down on the setting plate followed by its transfer to a conveyor belt. A disadvantage associated with this embodiment is that cooling of the base of the glass article makes it necessary to hold the article above the level of the setting plate. This means that the holders of the take-out mechanism are not available during this period, at any rate not for picking up further glass articles from a forming tool of the glass molding machine.
Cooling of the base of the glass article as it is being held above a setting plate is also previously disclosed in AT 0 321 522 B, although the cooling air in this case is conditioned with a low-temperature fluid, for example liquid CO2, N2 or even He, for the purpose of improving the cooling performance. However, this procedure is associated with a considerable additional plant-specific technical investment plus the additional costs of the fluid.
Previously disclosed in EP 0 149 890 A1 is a setting plate arrangement, in the setting plate of which a central orifice on the base side and an arrangement of radially oriented surface grooves, uniformly distributed in the circumferential direction and originating from an area beneath the base and extending to an area that is radially outside the base, are allocated to each hollow glass article to be cooled. The areas between the grooves provide a supporting surface for the glass article, which is also surrounded by an arrangement of slot-shaped nozzles that are concentric with the central orifice. The central orifice is subjected to negative pressure, so that a first flow of air for cooling the base of the glass vessel is produced from the area above the surface grooves and the aforementioned central orifice and into a suction pipe connected thereto. The setting plate forms the upper part of a chamber that is subjected to compressed air, so that a second flow of air is produced, emerging from the nozzles, uniformly surrounding the side walls of the glass article and cooling them. Both the suction pipe and the chamber are connected by the intermediate arrangement of controllable valves to the suction side and the pressure side of a fan, so that operation adapted to the working rate of the glass molding machine is possible. The application of negative pressure in particular is intended to help to improve the stability of the glass article as it stands upright including at a high throughput. Although cooling of the base of the glass article as it stands upright is achieved in this embodiment, a significant increase in the cooling efficiency is countered inter alia by the disadvantage of a small maximum difference in the pressure of a flow of cooling air that is dependent on a suction effect as the driving force.
These previously disclosed setting plate arrangements thus require a compromise between the adequate base cooling of the articles and a risk of damage associated with transport. As a result, they do not offer at least any easily achievable approaches to a constructive design solution in order to increase the cooling performance and an associated throughput of glass articles.